In normal circumstances many microorganisms live on or in humans without causing harm to these humans. However, an increased number of certain microorganisms can be associated with a disease state. Particularly problematic is an increase in the number of microorganisms that produce significant concentrations of chemicals that are toxic to humans. Such toxins include: volatile sulfur compounds (VSCs), such as hydrogen sulfide, methyl mercaptan, dimethyl disulfide, and dimethyl sulfide; and polyamines, such as putrescine and cadaverine. Higher concentrations of volatile sulfur compounds and of polyamines are associated with certain disease states and with socially stigmatized conditions, such as halitosis, or bad breath. It would be desirable to enable facile simultaneous detection of volatile sulfur compounds and polyamines in order to facilitate detection of the presence of potentially pathogenic microorganisms and of disease states and conditions with which these microorganisms are associated.
The principal VSCs produced by oral bacteria are hydrogen sulfide (H2S) and methylmercaptan (CH3SH). H2S is produced by the bacterial enzyme L-cysteine desulthydrase, which degrades the amino acid L-cysteine to produce H2S, ammonium and 2-ketopropanate. The other major VSC, CH3SH, is produced by the action of the bacterial enzyme L-methionine gamma lyase, which breaks down the amino acid L-methionine to produce CH3SH, ammonium and 2-ketobutyrate. H2S levels have been reported to occur at levels as high as 2 mM in the gingival crevice of persons with severe periodontal disease.
In addition to VSCs, oral bacteria have also been shown to produce high levels of polyamines; chief among these are 1,4-diaminobutane (putrescine) and 1,5-diaminopentane (cadaverine). Putrescine is produced by the action of the bacterial enzyme ornithine decarboxylase, which degrades the amino acid L-ornithine to produce putrescine and carbon dioxide. Cadaverine is produced by the bacterial enzyme lysine decarboxylase, which breaks down the amino acid L-lysine to cadaverine and carbon dioxide.
Millimolar levels of these malodorous bacterial waste products have been reported in the gingival crevicular fluid (GCF) of persons with severe periodontal disease. Their presence imparts a foul odor to the breath of persons with the disease. In addition to being malodorous, VSCs have also been shown to be toxic and adversely affect a number of mammalian enzymes. Production of these waste products by bacteria residing on the dorsum of the tongue imparts a foul odor to expired breath, resulting in halitosis. Together these two classes of bacterial waste products combine to impart a foul odor to the breath of persons with halitosis and periodontal disease. The levels of these waste products in GCF correlate directly with the level of periodontal disease activity. The levels of these waste products in expired air correlate directly with the level of bad breath or halitosis.